But didn't she already confess to him back at the playground in the earlier chapter? She was fine with it then but now suddenly can't seem him as anything other than a girl? The motivations in this manga seem all over the place.
Bro, just take the presedents route, tell your direct family and close friends, then to everyone else make boy you disappear and then have girl you replace you. All the girls who like you seem to like the girly part of you anyways, hiding it is a pointless RN